As is also known in the art, an adaptive optic (AO) actuator provides means to correct a phase front on a pixel by pixel level.
As is also known, conventional AO actuators operate as so-called “reflective-mode” devices and are typically implemented via deformable mirrors or MEMS mirrors. With exception of liquid crystal cells, all known technologies for realizing an AO are inherently limited to reflective-mode operation.
Use of reflective-mode AO devices often results in unnecessarily complicated optical layouts. Furthermore, reflective-mode AO actuators are generally larger and heavier than desired for many applications. Additionally, such reflective-mode AO actuators are not as fast as desired, do not handle phase fonts with phase discontinuities do not have sufficient spatial resolution, and do not handle high levels of optical power.
Also, all mechanically based AOs suffer interactuator modulation, whereby the setting of one pixel affects the setting of adjacent pixels. This prevents such AOs from correcting wavefronts with discontinuous phase, as is common in atmospheres with high levels of turbulence. MEMS-based devices (e.g. such a those manufactured by Boston MicroMachines) offer the smallest known interactuator coupling of about 13%.
Prior-art transmissive AOs based on liquid crystal technologies, which alleviate a number of the difficulties with mechanical AOs, are known but suffer from low bandwidth and also variable response time from pixel to pixel.
It would, therefore, be desirable to provide an AO actuator that is compact, lightweight, high speed or at least having pixel speeds constant across the aperture, and high power in the preferred transmission-mode embodiment, and which works well with discontinuous phase fronts.